1. Field of the Invention
The present invention is directed to a method and an apparatus for forming a metallic sheet having a concave-convex profile by chemical vapor deposition (CVD), and more particularly to such method and apparatus for forming a metallic sheet such as a shearing foil of a dry shaver which has a number of hair introducing holes with a raised edge, or an ornamental metallic sheet with a concave-convex surface pattern.
2. Discussion of the Prior Art
A typical example of such metallic sheet having a concave-convex profile is an outer shearing foil formed with a number of hair introducing holes each surrounded by a raised rim or edge which is in shearing engagement with a complementary inner cutter. In the past, techniques for making such outer shearing foil with such hair introducing hole have been proposed as disclosed in the following prior art references.
(1) Japanese Patent Publication No. 60-55123 on Dec. 3, 1985; PA0 (2) Japanese Patent Publication No. 36-19556 on Oct. 17, 1961; and PA0 (3) Japanese Patent Publication No. 42-27388 on Dec. 25, 1967.
The prior art (1) is directed to a press-forming technique in which a blank metal sheet is press-formed into a suitable configuration between a die and a complementary ram followed by being trimmed or cut to obtain the profiled metal sheet having the hair introducing holes with raised edges from a blank metal sheet. This technique requires considerable care for eliminating undue deformation developed in the sheet during the press-forming process to assure a correct formation of a desired profile including the configuration and the size of the holes and the spacing between the adjacent holes, thus posing difficulty and inconvenience.
The prior art (2) is directed to an etching technique in which a blank metal sheet has its two opposite surfaces etched at particular portions while being masked in the respective surfaces. Therefore, this technique requires duplicate masking operations and etching operations or steps with respect to the opposite surfaces of the blank metal sheet with the corresponding difficulty in controlling an etching solution, which may also pose a problem.
The prior art (3) is directed to an electrodeposition technique in which an outer shearing foil is formed as being deposited on a substrate through repeated electrodeposition with the use of an electrical insulative material on the substrate. Also in this technique, there are required cumbersome masking and pre-electrodeposition steps on the substrate prior to forming the profiled metal deposition layer by the electrodeposition, which is found to be disadvantageous, in addition to the difficulty in controlling an electrodeposition solution.
Although not directed to the formation of the outer shearing foil for the dry shaver, Japanese Patent Publication No. 59-197560 issued on Nov. 9, 1984 teaches the chemical vapor deposition process for depositing a metal layer on a substrate with the use of a laser light. This process may be applicable to obtaining the separate metal sheet off the substrate, but it is found practically impossible with this process to obtain a profiled metal sheet having a number of holes with raised edges or other projections.